1. Field of the Invention
The present invention relates to a developing device, a process cartridge, a developer layer regulating member, and a developer layer regulating member attaching method.
2. Related Background Art
In electrophotographic image forming apparatuses such as a copying machine, a laser printer, and a facsimile machine, an electrostatic latent image is formed through selective exposure on an electrophotographic photosensitive drum that is uniformly charged by a charging device. Developer is deposited onto the thus formed electrostatic latent image by a developing device, thus developing the electrostatic latent image as a developer image. The developer image is then transferred to a recording medium, thus forming an image on the recording medium. Then, a cleaning device removes from the electrophotographic photosensitive drum any developer remaining on the surface after the transfer of the developer image, thus leaving the electrophotographic photosensitive drum ready for the next image forming process.
Conventionally, there has been adopted a process cartridge system in which an electrophotographic photosensitive drum and components acting on the electrophotographic photosensitive drum, such as charging means (charging device), developing means (developing device), and cleaning means (cleaning device), are integrated into a single cartridge that is detachably mounted to an electrophotographic image forming apparatus main body (hereinafter referred to as the “image forming apparatus main body”). The cartridge system realizes improved operability, allowing for easy maintenance on the above-described process means by the user himself. For this reason, the cartridge system is now widely adopted for an image forming apparatus main body.
In recent years, there has been increased demand for the miniaturization of an image forming apparatus main body. This also led to growing demand for the miniaturization of a process cartridge.
However, the sizes of components such as a developing roller that carries developer in a developing device, an electrophotographic photosensitive drum that is an image bearing member on which an electrostatic image is formed, etc., depend on the size of desired image formation, which inevitably puts a limit on the miniaturization of those components. This also puts a limit on the miniaturization of members acting on those components, for example, a developer layer regulating member that regulates the thickness of a developer layer on the circumferential surface of a developer roller.
Incidentally, of conventional developer layer regulating members, there is one in which, for example, a positioning portion and a fixing portion are arranged on the same plane as a mounting surface extending in the longitudinal direction parallel to a developing roller (JP H09-171303 A).
However, the regulation width in the longitudinal direction of the developer layer regulating member determines the developing width of the developer roller in accordance with the image formation region on the photosensitive drum. Therefore, there is a limit to the miniaturization of the developing roller.
Further, as to the positioning method for the developer layer regulating member, the surface where the fixation of the developer layer regulating member to the developing container is effected lies on the same plane as the plane parallel to the longitudinal direction of the developing roller. Moreover, a fitting portion for effecting positioning and a screw hole for effecting fixation are arranged in close proximity to each other in the lateral direction crossing the longitudinal direction of the developer layer regulating member. Therefore, there is a limit to achieving miniaturization of the developer layer regulating member through a reduction in the distance between the fitting portion and the screw hole by bringing them closer to each other.